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Sakti3 is one of Michigan’s most high-profile startups, whose solid state, lithium ion batteries have won funding from General Motors and Khosla Ventures and plaudits by MIT’s Technology Review.

Such technology could revolutionize electric cars by packing more energy into a battery that occupies much less space under the hood than existing batteries. With less battery weight to hold it down, an electric car could travel longer distances without having to recharge.

However, I recently came across two other technologies that could give Sakti3 a run for its money. They focus on the same problems-reducing the battery’s bulk while stuffing the car with more energy-but from completely different approaches.

Be careful. That’s not just a hood you’re sitting on: Volvo is funding a $5 million research project at the Imperial College in London to create composite materials that can store and distribute energy.

The strong, lightweight materials, made of carbon fibers and polymer resins, can essentially convert parts of the car, like the hood, trunk, or wheel wall, into extra fuel tanks. That means the car doesn’t need large (or as many) electric batteries to power the engine, allowing the vehicle to travel farther between recharges. Researchers estimate they can reduce the car’s weight by 15 percent.

And unlike conventional batteries, the composite materials don’t rely on chemical reactions to work their magic. Since each chemical reaction that enables a charge degrades the battery, Volvo’s batteries will theoretically last longer.

Researchers are also trying to apply the technology to cell phones and computers. For instance, a cell phone made of the composite materials could be as thin as a credit card because it doesn’t need a traditional battery.

“Cambridge Crude:” An MIT team in Cambridge, MA, led by A123 Systems founder Yet-Ming Chiang, is working on a new class of “semi-solid state” battery technology. The research combines the basic structure of aqueous-flow state batteries with the chemistry of lithium-ion batteries. (A123 Systems recently opened the largest lithium-ion battery manufacturing plant on the North American continent in Livonia, MI.)

The system converts a battery’s active solid state components (the positive and negative electrodes, called cathodes and anodes) into tiny particles suspended in a black goo-like liquid. The thick substance, which researchers affectionately dub Cambridge Crude, can hold more power than traditional flow batteries and is cheaper to manufacture than lithium batteries, the MIT team claims.

So when an electric car needs to refuel, drivers can either recharge the battery the normal way (plugging into an outlet) or pump in freshly charged Cambridge Crude. The result is a lighter, more energy-efficient electric car that can travel longer distances before it needs to recharge.

MIT has already licensed the technology to a startup called 24M Technologies, which spun out of A123 last summer. The company has raised $16 million in venture capital and federal research funding, including grants from the U.S. Defense Advanced Research Projects Agency (DARPA) and Advanced Research Projects Agency – Energy (ARPA-E).